Generating code from natural language description is an important but challenging task in artificial intelligence [1]}, [2]}, [3]}, [4]}. It is beneficial to various applications. For example, a programmer would like to “open the file, F1” in Python, but does not know how to implement it in the programming language. Hopefully, he or she can obtain the target code “f = open('F1', 'r')” by code generation.
